1. Field of the Invention
The present invention relates to a water treatment pad (hereinafter, sometimes referred to simply as a pad) used when an object to be drilled such as a concrete structure, stone, rock bed, or a steel structure is drilled by using a drilling tool such as a core drill or a hammer drill. More particularly, the present invention relates to a water treatment pad capable of being fixed quickly and firmly when being fixed to a drilling surface by making the pressure therein negative.
2. Description of the Related Art
As a device for drilling a concrete structure or the like, a drilling tool such as a core drill or a hammer drill has been known. When drilling is performed by using such a drilling tool, the rotating drilling tool is pressed against a predetermined drilling position of the concrete structure or the like, and is moved downward, by which a hole is formed. During this drilling work, chips and dust particles of concrete structure are generated. To prevent the chips and dust particles from scattering, the drilling work is generally performed while water is supplied to the drilling position. This supply of water is also useful for cooling the drilling tool. For the drilling work performed while water is supplied in this manner, a water treatment pad is used.
As shown in FIG. 14A and FIG. 14B, a water treatment pad 100 having a substantially cylindrical shape is placed on a drilling surface of the concrete structure or the like in a manner that surrounds the drilling position. Also, the water treatment pad has a drain 102 in the side surface of a pad body 101 so that water in the pad can be drained. When drilling is performed by using this water treatment pad 100, drilling is performed while water is supplied to the drilling position through a hollow part in the drilling tool and the supplied water is drained through the drain 102. By doing this, chips and dust particles produced during the drilling work are discharged from the drilling position together with water, by which chips and the like can be prevented from scattering. When the water is drained, a vacuum cleaner (hereinafter, referred to simply as a cleaner) is connected to the drain 102 to efficiently drain the water, by which the water is drained forcibly so often by the attraction force of the cleaner.
For the drilling work using the water treatment pad, the pad must be fixed to prevent the deviation of pad caused by vibrations of the rotating drilling tool and the leakage of machining water caused by the deviation of pad. As a method for fixing the pad, fixing methods using fixtures as shown in FIG. 15A, FIG. 15B and FIG. 15C are available. Each of the pad fixtures partially presses the pad against the drilling surface of an object to be drilled to fix the pad on the drilling surface by utilizing a resin, an elastic body such as a spring, or a screw. The pad fixture is used by adjusting the installation position and the number of installed fixtures according to the pad size and the drilling position.
The pad fixing method using the fixture is easy to carry out in principle, and is generally in widespread use. However, the water treatment pad has no unified standard, and the size thereof varies among the manufacturers and the like. Therefore, a fixture having optimum specifications for each pad must be prepared, which results in poor convenience. Also, when the fixture is installed, the optimum installation position must be chosen considering the center of gravity etc. of the pad. However, for example, in the case where it is desired to drill a hole at a position near a wall, the optimum installation position cannot sometimes be chosen depending on the drilling position.
Thereupon, as a method for fixing the water treatment pad, besides the method in which the above-mentioned external device is used, a method is also used in which the pad is attracted to the drilling surface by making the pressure therein negative. As described above, when the drilling work is performed, the cleaner is generally used to discharge the supplied machining water and the abatements. The attraction due to the cleaner makes the pressure in the pad negative not a little, so that the pad can also be fixed by the attraction due to the cleaner.
As the water treatment pad, besides the above-described cylindrical pad having a single internal construction as shown in FIG. 14A and FIG. 14B, a pad having a double construction. which is an improvement on the above-described cylindrical pad, is known from the viewpoint of improvement in draining efficiency (refer to Japanese Patent Application Laid-Open No. 2003-127131). This water treatment pad having a double construction is formed with an inner wall 202 circumferentially between a drain 101 and an opening 201 of a pad body as shown in FIG. 16. Thereby, water is attracted and drained via a pressure space formed between the inner surface of the pad body and the inner wall 202. In this water treatment pad, since the communication of the interior of the pressure space with the outside air is restricted, the attraction due to the cleaner easily makes the pressure in the pad negative, so that the draining efficiency can be improved. Also, a further improved water treatment pad having a double construction is described in Japanese Patent Laid-Open No. 2008-68328.
Also, the applicant of the present invention has invented and filed a water treatment pad having a still higher draining efficiency than the above-described pad having a double construction. In this water treatment pad, a predetermined inner wall plate is provided near the drain on a pad body having a single construction so that a double construction is formed partially and the pressure space is made small, by which the attraction force of cleaner is utilized effectively. In this pad also, fixation by the negative pressure therein is possible (refer to Japanese Patent Laid-Open No. 2008-162121).
However, in the above-described conventional water treatment pad, the reduction in pressure in the pad is insufficient probably because the improvement in draining efficiency is the main objective. Especially in the case where the drilling operation using a core drill proceeds and the object to be drilled is penetrated, the negative pressure in the pad cannot be kept because of the inflow of air through the penetrated hole, by which the pad cannot be fixed in some cases. Also, the pad should be fixed quickly after the start of drilling work. However, it takes much time to make the pressure in the pad negative, so that it has also been demanded that the quickness of pad fixation be improved.